JP 2006-98246 A discloses a vehicle position measuring device comprising GPS receiving means for receiving GPS signals, first calculating means for calculating a first position of the vehicle based on the GPS signals, travel distance detecting means for detecting a travel distance of the vehicle, direction detecting means for detecting a traveling direction of the vehicle and second calculating means for calculating a second position of the vehicle based the travel distance detected by the travel distance detecting means and the traveling direction detected by the direction detecting means, wherein said device further comprises determining means for determining the reliability of the first position of the vehicle, and said device corrects the second position of the vehicle by the first position of the vehicle considering the reliability determined by the determining means and a calculation time of the first calculating means.
By the way, various ways of measuring the position of the mobile station using the signals from the satellites, INS sensor, etc., have been proposed; however, a technique for combining plural of the measuring ways while considering the advantages and disadvantages of these ways so as to efficiently perform determination with high accuracy has not been proposed.